Stress control mechanism by fiber distribution

Abstract

Abstract This study aims to determine the optimal design of fibers that can minimize circumferential bending stress from the morphology of “bamboo,” which is considered a “natural functionally graded material (FGM)” because vascular bundles are distributed unevenly across its cross-section. Further, vascular bundles are crucial for determining the mechanical properties of bamboo, and their distribution is not random. This study analyzes bias distribution from the viewpoint of structural mechanics. Longitudinal splitting is a dominant failure mode in both bamboo and fiber composites, it is mainly caused by circumferential bending tensile stress. The bamboo was modelled as a hollow cylinder, and a circumferential bending stress equation was formulated. As a result, the vascular bundles distribution of the bamboo minimized the circumferential bending stress on the inner surface of the cross-section throughout the culm. These suggest that bamboo is a smart plant that can control its distribution based on regions more prone to failure, e.g., where cracks occur first on the inner surface. This study can help obtain the optimal stress-controlled design of fiber-reinforced composites and understand the morphological design of bamboo.